Re: [Xen-devel] [PATCH] x86/efi: Reserve EFI properties table

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

On 05/15/2017 02:52 PM, Julien Grall wrote:
> Hi Andrew,
>
> On 08/05/17 17:29, Andrew Cooper wrote:
> > On 08/05/17 17:17, Ross Lagerwall wrote:
> > > Some EFI firmware implementations may place the EFI properties table in
> > > RAM marked as BootServicesData, which Xen does not consider as reserved.
> > > When dom0 tries to access the EFI properties table (which Linux >= 4.4
> > > does), it crashes with a page fault.
> > The pagefault is just a side effect of Linux blindly assuming that the
> > ioremap() request succeeded.
> >
> > From Xen's point of view, Dom0 tries to map a page which doesn't belong
> > to dom_xen, resulting a permission failure.
> >
> > >   Fix this by unconditionally
> > > marking the EFI properties table as reserved in the E820, much like is
> > > done with the dmi regions.
> > >
> > > Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
> > Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> >
> > This is probably also 4.9 material.
> It looks like Jan had some comments on this patch. I haven't seen any
> reply from Ross, I will wait before looking from a release perspective.
Jan had some comments on that patch but essentially NAKed it on
principle so I don't think it will be going into 4.9.

Thanks,
--
Ross Lagerwall

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